Interactive effects and modeling of some processing parameters on milling, cooking, and sensory properties for Nigerian rice using a one-step rice milling machine

Effect of microwave drying of paddy on milling characteristics, cooking quality, and microstructure of rice

Effect of microwave drying on milling, cooking, and microstructure characteristic of paddy rice in comparison to hot air drying was assessed in the present study. Results revealed that modified microwave drying significantly (P < 0.05) affected the milling quality of paddy. Raw paddy had head rice recovery of 49.63%, while after microwave drying, the head rice recovery increased by 6.73% in comparison to hot air drying. Microwave drying brought significant changes in the colour characteristic of rice as it had total colour change of 13.50 in comparison to 10.93 by hot air drying. Cooking time and water uptake ratio after microwave drying increased to 31.46 min and 3.16%, in comparison to 27.05 min and 2.65% for hot air dried samples, respectively. Scanning Electron Microscope images revealed that both hot air and microwave dried rice had a coarse surface and large starch particles, while starch structure was more damaged in hot air drying, however, agglomeration of protein-starch matrix was more uniform in microwave dried samples due to modification of the microwave applicator that prevented thermal decomposition. It was recommended that paddy may be dried using a modified microwave applicator with a shorter duration and a better quality.